Ceramic compositions are receiving widespread acceptance for use as cutting tools and cutting tool inserts because of their excellent wear properties. Unfortunately, many of the ceramic materials heretofore known to the prior art are quite brittle and their use has been primarily confined to light duty work such as finish machining. Application of such prior art ceramic materials to heavy duty cutting operations has been restricted due to the lack of toughness of such materials resulting in tool fracture under such severe operating conditions.
In order to overcome such prior art problems, various compounds have been incorporated in an alumina ceramic to achieve increased toughness while retaining acceptable wear resistance. These additives are detailed in the following references:
Nils Claussen, et al., CERAMIC BULLETIN, Vol. 56, No. 6 (1977), Effect of Induced Microcracking on the Fracture Toughness of Ceramics.
D. Greve, et al., CERAMIC BULLETIN, Vol. 56, No. 5 (1977), Thermal Diffusivity/Conductivity of Alumina with a Zirconia Dispersed Phase.
Nils Claussen, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol. 59, No. 1-2, Jan.-Feb. 1976, Fracture Toughness of Al.sub.2 O.sub.3 with an Unstabilized ZrO.sub.2 Dispersed Phase.
Roll Turning and Resurfacing with Oxide-Carbide Ceramics, by F. C. Holtz and F. L. Frobert, The Valeron Corporation, presented at New Developments in Tool Materials and Application Symposium on March 21-22, 1977, Chicago.
U. Dworak et al., Ber. DT. Keram. Ges. 55 (1978) Nr. 2; Mechanical Strengthening of Multiphase Ceramics as Illustrated by the ZrO.sub.2 --ZrO.sub.2 /Al.sub.2 O.sub.3 --ZrO.sub.2 /Al.sub.2 O.sub.3 --TiC Systems.